function my_ajax(Url,type,callback){
	var xhr = new XMLHttpRequest();
		xhr.open(type,Url);
		xhr.send()
		xhr.addEventListener("readystatechange",function(){
			if(xhr.readyState==4){
				if(xhr.status==200){
					var res = JSON.parse(xhr.responseText)
					callback(res)
				}
			}
		})
}
